But forecasters said the 350-mile-wide storm's slow progress across North and South Carolina could leave much of the region under water.

Debris lies on the ground at a Royal Dutch Shell Plc gas station damaged during Hurricane Florence in Wilmington, North Carolina, U.S., on Friday, Sept. 14, 2018.

Alex Wroblewski | Bloomberg | Getty Images

Tropical storm Florence lumbered inland on Saturday, knocking down trees, flooding rivers, and dumping sheets of rain in the Carolinas where the death toll climbed to at least eight.

It diminished from hurricane force as it came ashore, but forecasters said the 350-mile-wide storm's slow progress across North and South Carolina could leave much of the region under water in the coming days.

By Saturday afternoon, Florence was inching west at 3 mph (6 kph), with its center located about 50 miles (85 kilometers) west of Myrtle Beach, South Carolina. Forecasters say prolonged rainfall from Florence could produce catastrophic flash flooding and significant river flooding.

Tropical storm-force winds stretched up to 150 miles (240 kph) from the storm's center.

"This storm is relentless and excruciating," North Carolina Governor Roy Cooper told CNN late on Friday. "There is probably not a county or a person that will not be affected in some way by this very massive and violent storm."

A mother and baby were killed when a tree fell on their home in Wilmington, North Carolina. The child's injured father was taken to hospital. In Pender County, a woman died of a heart attack; paramedics trying to reach her were blocked by debris.

Two people died in Lenoir County. A 78-year-old man was electrocuted attempting to connect extension cords while another man died when he was blown down by high winds while checking on his hunting dogs, a county spokesman said.

Search and Rescue workers from New York rescue a man from flooding caused by Hurricane Florence in River Bend, North Carolina.

NYC Emergency Management | Reuters

In New Bern, North Carolina, the storm surge overwhelmed the town of 30,000 which is located at the confluence of the Neuse and Trent rivers.

Officials in New Bern, which dates to the early 18th century, said more than 100 people were rescued from floods and the downtown was under water by Friday afternoon.

Resident Jay Manning said he and his wife watched with alarm as water filled the street.

"We moved all the furniture up in case the water comes in but the water seems to be staying at the edge of the driveway," he said, adding that if the wind picks up and the rain keeps coming, that could change. "My wife's in a panic right now."

Dan Eudy said he and his brother were awakened on Thursday night by the sound of a boat ramming against his front porch.

Eudy said his family stayed in their home partly to protect their house. "And we had no belief it would be as significant an event as it was," he said. "This is a 500- or 1,000-year event."

Heavy rain

Florence was a Category 3 hurricane on the five-step Saffir-Simpson scale with 120-mph winds on Thursday. It was downgraded to a Category 1 hurricane before coming ashore near Wrightsville Beach close to Wilmington, North Carolina.

The National Hurricane Center (NHC) downgraded it to a tropical storm on Friday, but warned it would dump as much as 30 to 40 inches (76-102 cm) of rain on the southeastern coast of North Carolina and part of northeastern South Carolina.

Atlantic Beach on North Carolina's Outer Banks islands had already received 30 inches of rain, the U.S. Geological Survey said.

North Carolina utilities estimated that as many as 2.5 million state residents could be left without power, the state's Department of Public Safety said.

The White House said on Friday that President Donald Trump had spoken with state and local officials, assuring them the federal government was prepared to help. Trump plans a visit to the region next week.

Florence was moving west-southwest at about 5 mph (7 km/h), with its centre located over eastern South Carolina. The storm is expected to turn west and then north moving through the Carolinas and the Ohio Valley by Monday, the NHC said early on Saturday. Significant weakening was expected over the weekend.

Florence was one of two major storms threatening millions of people on opposite sides of the world. Super Typhoon Mangkhut was expected to hit an area in the Philippines on Saturday that would affect more than 5 million people.